/Engine/Source/Runtime/Experimental/GeometryCollectionEngine/Public/GeometryCollection/GeometryCollectionObject.h
Attach a Static Mesh exemplar for embedded geometry, if that mesh has not already been attached. Return the exemplar index.
int32 AttachEmbeddedGeometryExemplar ( const [UStaticMesh](API\Runtime\Engine\Engine\UStaticMesh) * Exemplar )